Influence of Internal Mixing Condition on Properties of Conductive Biocomposites between Poly(Lactic Acid) and Hybrid Graphene

2021 ◽  
Vol 889 ◽  
pp. 38-43
Author(s):  
Nattakarn Hongsriphan ◽  
Nattamon Thaisa ◽  
Wanutchaya Yuenyong ◽  
Siriporn Pruekchat ◽  
Sorawit Duangsripat
Keyword(s):  
Electrical Resistivity ◽  
Lactic Acid ◽  
Weight Ratio ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Rotor Speed ◽  
Mixing Condition ◽  
Fixed Weight ◽  
Significant Difference ◽  
Internal Mixer

The objective of this research was to investigate the influence of mixing condition on mechanical, thermal, and electrical properties of the biocomposite between poly(lactic acid) (PLA) and hybrid graphene (HG). PLA/HG composites of a fixed weight ratio (95/5 wt%) was mixed using an internal mixer, which the mixing temperatures (170, 180 and 200°C) and the rotor speeds (40, 60 and 80 rpm) were varied. It was found that the increase of E' before glass transition was attributed to the reinforcing effect of the HG. The faster the rotor speed was the higher storage modulus (E') was achieved at the lowest mixing temperature. The E' did not linearly depend on the rotor speed when mixing at higher temperature. As expected, mixing HG into PLA reduced the surface electrical resistivity. The mixing at 170°C with any rotor speed and mixing at 180°C with rotor speed of 40 or 60 rpm produced the composites in the same surface electrical resistivity, however, there was no significant difference when mixing at 200°C. From DSC analysis, there was a trend that the degree of crystallinity of the PLA/HG composites prepared at the lowest mixing temperature was higher than those prepared at the relatively higher mixing temperatures.

Effect of cellulose nanofibers from cassava pulp on physical properties of poly(lactic acid) biocomposites

2019 ◽  
Vol 33 (8) ◽  
pp. 1094-1108
Author(s):  
Thanh Chi Nguyen ◽  
Chaiwat Ruksakulpiwat ◽  
Yupaporn Ruksakulpiwat
Keyword(s):  
Lactic Acid ◽  
Cellulose Nanofibers ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Melt Mixing ◽  
Cassava Pulp ◽  
Lower Temperature ◽  
Alkali Hydrolysis ◽  
Internal Mixer

Biocomposites of poly(lactic acid) (PLA) and cellulose nanofibers (CNFs) extracted from cassava pulp were successfully prepared by melt mixing in an internal mixer. CNFs were prepared from cassava pulp by submitting to alkali hydrolysis, bleaching treatment, and acid hydrolysis. The compatibility between CNFs and PLA matrix was improved using glycidyl methacrylate (GMA) grafted PLA (PLA-g-GMA) as an effective compatibilizer. Higher elongation at break and impact strength of PLA/PLA-g-GMA/CNFs biocomposites was achieved compared to that of neat PLA. PLA-g-GMA shows a strong effect on the crystallization behavior of the biocomposites. The PLA/PLA-g-GMA/CNFs biocomposites induce cold crystallization to take place at lower temperature. Higher degree of crystallinity of PLA/PLA-g-GMA/CNFs biocomposites was obtained compared to PLA/CNFs biocomposites. The mechanical and thermal properties of PLA/CNFs biocomposites at various ratios were investigated. With increasing CNFs contents, the modulus of the biocomposites increases. Thermal stability of PLA/CNFs and PLA/PLA-g-GMA/CNFs biocomposites did not change significantly compared to that of neat PLA.

Effect of Poly(D-Lactic Acid)-co-Polyethylene Glycol on the Crystallization of Poly(L-Lactic Acid)

2017 ◽  
Vol 751 ◽  
pp. 283-289 ◽  
Author(s):  
Ployrawee Kaewlamyai ◽  
Amornrat Lertworasirikul
Keyword(s):  
Lactic Acid ◽  
Polyethylene Glycol ◽  
Weight Ratio ◽  
Crystallization Rate ◽  
Heat Stability ◽  
Nucleating Agent ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Infrared Spectrometry ◽  
Scanning Calorimetry

Poly (lactic acid) (PLA) is a biopolymer derived from renewable resources and can be disposed of without creating harm to the environment. PLA can be formed by thermoplastic processes and has good mechanical properties. However, its disadvantages are a high crystallization temperature, slow crystallization rate, poor heat stability and low ductility. In the past, it was found that poly (D-lactic acid) (PDLA) can form complexes with poly (L-lactic acid) (PLLA) and the complexes could accelerate the crystallization and increase the degree of crystallinity of the PLA, but decrease the ductility. It is known that polyethylene glycol (PEG) can improve the ductility of PLLA. In this research, PDLA was copolymerized with PEG in an attempt to improve both crystallization behavior and ductility of PLLA. Poly (D-lactic acid)-co-polyethylene glycol (PDEG) was synthesized by ring opening polymerization using D-lactide and PEG at a D-lactide:PEG weight ratio of 10:3. The PDEG was blended with PLLA with a PDEG content of 0wt% to 50wt% by melt blending process. Fourier transform infrared spectrometry (FT-IR) and X-Ray diffractometry (XRD) confirmed the stereocomplex formation between PDEG and PLLA. Characterization by differential scanning calorimetry (DSC) revealed that crystallization temperatures of the blends were decreased in the presence of PDEG. Storage moduli and tan of the blends obtained from dynamic mechanical analysis (DMA) decreased as PDEG content increased. Polarized optical microscopy (POM) micrographs of blends with PDEG content of 1wt% to 5wt% obviously showed that crystallization rate was increased. PDEG has the potential to be an effective nucleating agent and efficient plasticizer for PLLA.

scholarly journals Hemp Fibre Reinforced Poly(Lactic Acid) Composites

2007 ◽  
Vol 29-30 ◽  
pp. 337-340 ◽  
Author(s):  
M.A. Sawpan ◽  
K.L. Pickering ◽  
Alan Fernyhough
Keyword(s):  
Lactic Acid ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Hemp Fibre ◽  
Reinforcing Material ◽  
Fibre Loading ◽  
The Degree Of Crystallinity

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

Response of Modified Poly(lactic acid) to Microwave Radiation

2012 ◽  
Vol 488-489 ◽  
pp. 1393-1397
Author(s):  
Buranin Saengiet ◽  
Wasin Koosomsuan ◽  
Phassakarn Paungprasert ◽  
Rattikarn Khankrua ◽  
Sumonman Naimlang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Lactic Acid ◽  
Microwave Radiation ◽  
Food Packaging ◽  
Impact Resistance ◽  
Poly Lactic Acid ◽  
Polypropylene Glycol ◽  
Heat Accumulation ◽  
The One ◽  
Internal Mixer

The frozen instant food packaging is the one of disposal product, which produced from petroleum–based plastic and has been accumulated worldwide pressuring on the environment. Therefore, the biodegradable plastics have become key candidates in this application. Poly(lactic acid) (PLA) was regarded as one of the most promising biodegradable polymer due to its good mechanical properties. The aim of this work was to study on the freezability and microwavability of PLA through crosslink reaction. For the improvement of the processibility of PLA, hyperbranched polymer (HBP) and polypropylene glycol (PPG) were used as plasticizer. Then the crosslinking of PLA was introduced by addition of peroxide (Luperox101) and triallyl isocyanurate (TAIC) in an internal mixer. Neat and modified PLA samples were characterized and testing for mechanical properties. From the gel content results, it was showed the increased value with the increased content of TAIC due to the denser crosslinked structure of polymer. This result was confirmed by FT-IR spectra. All modified PLA samples showed the higher %strain at break than neat PLA. In addition, impact resistance in frozen state showed the results of modified PLA with 0.1wt% of peroxide and 0.15 wt% of TAIC, was higher than neat PLA. Moreover, this composition also showed the highest microwave response and heat accumulation was suppressed when the specimen was immersed in the water during the test. From the results obtained in this work, the further investigation is needed to pursue and elucidate the relationship between the polymer structure and heat absorption when materials undergo the microwave radiation.

Characterization of Electrospun Poly(Lactic Acid)/polyaniline Blend Nanofibers

2011 ◽  
Vol 332-334 ◽  
pp. 317-320 ◽  
Author(s):  
Hui Qin Zhang
Keyword(s):  
Lactic Acid ◽  
Composite Nanofibers ◽  
Weight Ratio ◽  
Electrospinning Process ◽  
Poly Lactic Acid ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Ft Ir

In this study, composite nanofibers of polyaniline doped with dodecylbenzene sulfonic acid (PANI-DBSA) and Poly(lactic acid) (PLA) were prepared via an electrospinning process. The surface morphology, thermal properties and crystal structure of PLA/PANI-DBSA nanofibers are characterized using Fourier transform infrared spectroscopy (FT-IR), wide-angle x-ray diffraction (WAXD) and scanning electron microscopy (SEM). SEM images showed that the morphology and diameter of the nanofibers were affected by the weight ratio of blend solution.

scholarly journals An openwork like structures of polylactide – manufacturing and properties

2018 ◽  
Vol 44 ◽  
pp. 00165 ◽  
Author(s):  
Karolina Sobczyk ◽  
Karol Leluk
Keyword(s):  
Lactic Acid ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Weight Ratio ◽  
Electrospinning Process ◽  
Poly Lactic Acid ◽  
Process Conditions ◽  
Fiber Morphology

Poly(lactic acid) electrospinning tests were carried out under various process conditions. Openwork structures with a high surface area to weight ratio have been obtained. Changing the parameters of the PLA electrospinning process resulted in products with different fiber morphology.

Toxicity Evaluation of Graphene and Poly(Lactic-Acid) Using a Nematode Model

2019 ◽  
Vol 290 ◽  
pp. 101-106
Author(s):  
Cin Kong ◽  
Azzahraa Izzati Aziz ◽  
Akesh Babu Kakarla ◽  
Ing Kong ◽  
Wei Kong
Keyword(s):  
Lactic Acid ◽  
Corn Starch ◽  
Feeding Activity ◽  
Reproductive Rate ◽  
Poly Lactic Acid ◽  
Mechanical And Thermal Properties ◽  
Live Animal ◽  
Pumping Rate ◽  
C Elegans ◽  
Significant Difference

Graphene has gained tremendous attention due to its unlimited potential in various applications while poly(lactic acid) (PLA) is a biodegradable thermoplastic polyester produced from fermenting corn starch. The incorporation of graphene into PLA has been proven to exhibit excellent mechanical and thermal properties. However, there are not many reports on the potential toxic effect of these materials towards living organisms. In this study, we investigated the possible toxicity of graphene and PLA-graphene in a live animal model, the nematode Caenorhabdits elegans (C. elegans). Alive adult worms were exposed directly to graphene and PLA-graphene across a range of concentrations from 50 µg/mL to 1000 µg/mL. After certain hours of exposure, the pharyngeal pumping rate (indicative of the C. elegans feeding activity), reproductive rate and lifespan of the worms were determined and compared to the untreated worm population. At all concentrations tested, both graphene and PLA-graphene do not affect the feeding rate of the nematode. Additionally, there was no significant difference between the lifespan of worms exposed to graphene and PLA-graphene as compared to the untreated control population (p>0.05). We examined the effect of graphene on nematode’s ability to reproduce and no reduction in progenies was detected (p>0.05). Taken together, our findings suggest that graphene and PLA-graphene do not possess a negative effect on the feeding activity, reproduction and overall lifespan of the host, indicating that these materials are safe to living organism at concentration up to 1000 µg/mL.

Morphology and Mechanical Properties of Poly(Lactic Acid) with Propylene-Ethylene Copolymer and α-Cellulose

2019 ◽  
Vol 947 ◽  
pp. 200-204
Author(s):  
Sirirat Wacharawichanant ◽  
Patteera Opasakornwong ◽  
Ratchadakorn Poohoi ◽  
Manop Phankokkruad
Keyword(s):  
Lactic Acid ◽  
Young’S Modulus ◽  
Interfacial Adhesion ◽  
Morphological Analysis ◽  
Young's Modulus ◽  
Spherical Shape ◽  
Poly Lactic Acid ◽  
Compression Method ◽  
Ethylene Copolymer ◽  
Internal Mixer

This work studied the improvement of poly (lactic acid) (PLA) properties by adding propylene-ethylene copolymer (PEC) and α-cellulose (AC). The PLA blends and composites were melt mixed by an internal mixer and molded by compression method. The morphological analysis observed the phase separation of PLA/PEC blends due to minor PEC phase dispersed as spherical shape in PLA phase, indicating a poor interfacial adhesion between PLA and PEC phases. The incorporation of AC did not improve the compatibility of polymer blends. Young’s modulus and tensile strength of PLA blends reduced with increasing amount of PEC because the elastics of ethylene molecules in PEC structure. Young’s modulus of PLA/PEC/AC composites increased with increasing AC contents. The stress at break of the PLA/PEC blends was improved with the presence of AC. The strain at break of PLA/PEC blends increased with increasing PEC contents, and the presence of AC showed the decrease of strain at break of PLA/PEC blends.

Synthesis of a Compatibilizer and the Effects of Monomer Concentrations

2014 ◽  
Vol 554 ◽  
pp. 96-100 ◽  
Author(s):  
Nur Syazana Abdullah Sani ◽  
Agus Arsad ◽  
Abdul Razak Rahmat
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Lactic Acid ◽  
Fourier Transforms ◽  
Poly Lactic Acid ◽  
H Nmr ◽  
Grafting Reaction ◽  
Melt Grafting ◽  
Infrared Spectrometer ◽  
Internal Mixer ◽  
Grafting Degree

The aim of this research was to modify Poly (lactic acid) (PLA) and Natural Rubber (NR) using maleic anhydride (MA). The preparation was carried out using internal mixer by free radical melt grafting reaction to produce PLA-g-MA and NR-g-MA as a compatibilizer. The effects of concentrations of MA (3-12 phr) were studied in details. The samples structure of copolymers were then characterized using 1H nuclear magnetic resonance (1H-NMR) and Fourier transforms infrared spectrometer (FTIR). Quantities of grafted MA (% grafting) were characterized by titration analysis and when increasing the monomer used, the quantities of the grafted MA on PLA and NR molecules also increased. The optimum grafting degree for PLA-g-MA and NR-g-MA was at 9 phr of MA with value of 1.63% and 5.02%, respectively.

Crystallization and Thermal Degradation of Green Nanocomposites Based on Lignin Coated Cellulose Nanocrystals and Poly(Lactic Acid)

2017 ◽  
Vol 737 ◽  
pp. 256-261 ◽  
Author(s):  
Martin Boruvka ◽  
Luboš Bĕhálek
Keyword(s):  
Lactic Acid ◽  
Cellulose Nanocrystals ◽  
Raw Material ◽  
Degree Of Crystallinity ◽  
Poly Lactic Acid ◽  
Crystalline Cellulose ◽  
Melt Crystallization ◽  
Scanning Calorimetry ◽  
Wide Range ◽  
Twin Screw

Cellulose is almost inexhaustible source of raw material comprising at least one-third of all biomass matter. Through deconstruction of cellulose hierarchical structure can be extracted highly crystalline cellulose nanocrystals (CNC) with impressive properties. However, the main barrier in the processing of the nanocomposites based on CNC is their inhomogeneous dispersion and distribution in the non-polar polymer matrix. In this paper is this problem addressed by use of novel hydrophobic lignin coated CNC as a biobased nucleation agents in poly (lactic acid) (PLA) nanocomposites. These green nanocomposites based on natural plant derived substances have enormous potential to replace materials originated from non-renewable resources and show promise of providing degradation back into the environment when they are no longer needed. Resulted composites prepared by twin screw extrusion and injection moulding were characterized by means of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The addition of L-CNC (1, 2 and 3 wt. %) into PLA increased melt crystallization enthalpy and decreases the cold crystallization enthalpy. The degree of crystallinity (cc) increased from 5.6 % (virgin PLA) to 8.5 % (PLA/1-L-CNC), 10.3 % (PLA/2-L-CNC) and 10.7 % (PLA/3-L-CNC). The wide range of degradation temperatures of lignin coating has been observed starting at 100 °C.

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